Most mill decks are mono blue or blue-black, with blue-white not really getting in on that side of win conditions
In Yu-Gi-Oh, Seto Kaiba gloats that his Dragon-type deck, specifically his Blue-Eyes White Dragon card, is significantly stronger than any monster card that Yugi owns
Planeswalkers like Elspeth, Storm Slayer, Elspeth, Knight-Errant, and The Wandering Emperor usually complement a creature strategy well by pumping your creatures, giving evasion, or destroying opposing creatures
Furthermore, it can summon a tuner from the GY when it is summoned, which allows players to have multiple tuners in play if they want to continue Synchro summoning throughout the turn
In that regard, it's The MimeoplasmThe Mimeoplasm that best fits the precon, so we'll upgrade the deck with that in mind
Just check out Refurbished Familiar, Valkyrie Aerial Unit, and Thought Monitor